CAT Control: Uses the serial port RS-232 send and receive data lines to send commands and receive responses from the transceiver needed for rig control (frequency, filter settings, etc). The IF232 converts the +/- voltage levels used on the computer RS-232 interface to 0/+5 Volt levels needed by the transceiver.

Serial Port PTT control: Uses one of the RS-232 control lines on the serial port to control the transceiver's PTT line. In general, the +/- RS-232 control voltage operates a transistor that grounds the PTT line for transmit. Some software and some transceivers can operate PTT from CAT control commands so that you don't need to dedicate a serial port to PTT control. This is not very typical however.

Sound Card Data: This is where the communications occurs. The sound card converts the digital data to audio tones which are delivered to the transmitter audio input. It also converts audio tones from the receiver output back into digital data that can be displayed on the computer.

PTT VOX control: When the sound card outputs an audio tone to the transmitter, the VOX control operates a transistor that grounds the transceiver's PTT line and places it into transmit mode.

USB-Serial Converters: For serial port PTT control or CAT control the computer can use either a legacy RS-232 serial port (usually a 9-pin D connector) or it can use a USB-SERIAL converter and a Virtual Com Port driver that makes the USB port look like a legacy RS-232 serial port at the software level. That lets legacy software interface with the USB port even though the software knows nothing about USB. The Rigblaster PnP apparently builds the USB-Serial converter into the Interface as well as including a sound card in the Interface.

Sound Card: The sound card can be built into the computer or it can be built into the interface as in the Tigertronics SignaLink-USB. If built into the computer you will generally need to dedicate a serial port to PTT control. The SignaLink has a vox PTT circuit built into the interface along with the sound card so no serial port is needed for PTT control.

Rig (CAT) Control: A separate RS-232 serial port will need to be dedicated for rig control and the software must be designed to interface with this port and it must have rig control functions for your particular radio (commands differ between different manufacturers).

I just got my General license and bought a used Kenwood TS-450S, and I'd like to try using it with digital modes. The owners manual is a little vague, and searches here haven't really told me what I need.

From what I can see if I want to only do CW and RTTY, all I need is the IF-232 or equivalent, is that correct? Also, I'm thinking if I want to do PSK or MFSK, etc. then I'd also need a TNC like a Rigblaster or Signalink in addition to the IF-232?

Thanks,Mike

There are many options and the most popular seem to be the signalink and rigblaster. I own both and find the signalink usb to be more convenient. With my TS-690 (which is a TS-450 w/6m) I purchased a CAT control cable and CW keying interface from W1GEE, or you can make them, but they are inexpensive enough for all but the cheapest cheapskates.

The details you guys (especially AA4PB) have mentioned is great--thanks very much! I work on computers for a living so I have no problem with serial/com ports. I think I understand much better now about rig control. I had mistakenly assumed that boxes like the Signalink USB did that as well as generated the sound output, but I see now that's not the case.

I've seen a couple of different types of the cables that replace the IF232c, but provide a USB connection instead of conventional 9 pin , and I think I'll order one of those. I've ordered a Signalink USB from DX Engineering, so that should be getting here soon.

Thanks--I found a separate computer control manual that Kenwood published for the TS-450 and that mentioned the baud rate and stop bits and other stuff. It's really more of a programmer's guide to serial communication with the rig, but it gave me what I needed.

I just got my General license and bought a used Kenwood TS-450S, and I'd like to try using it with digital modes. The owners manual is a little vague, and searches here haven't really told me what I need.

From what I can see if I want to only do CW and RTTY, all I need is the IF-232 or equivalent, is that correct? Also, I'm thinking if I want to do PSK or MFSK, etc. then I'd also need a TNC like a Rigblaster or Signalink in addition to the IF-232?

Thanks,Mike

Rigblaster / Signalink are not TNCs. They are simply sound card interfaces that allow a option port on the radio to 'talk' to the discrete lines in a serial port on a PC to engage PTT/CW keying and interface the radio to the sound card audio/line in/out to receive and transmit audio tones for digital modes via SSB.

Unless the IF232 is a whole different animal than most serial converter interfaces sold by radio manufacturers, it is only needed for CAT control of the radio (i.e. change freqs, modes, etc.)

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